It's widely believed that the Conservaives won the Uxbridge by-election because of motorists who were annoyed by the London mayor's ultra low emission zone. With a general election looming, both main english parties want to harness "driver power". But how did the vote of car and van owners become so important? Does the independence driving brings lead to a libertarian attitude? Or is that combative attitude caused by drivers feeling that they have been used as cash-cows by successive governments, which have gladly taken their road tax and fuel duty. But that power balance is also set to change, with the eventual electrification of all UK vehicles. Could road pricing replace fuel duty - and how will motorists respond? Presenter: Chris Bowlby Producer: Jim Frank Editor: Clare Fordham